Navicular stress fracture or something else?

I have been running very consistently last 3 years and done a few ironman races and soe open marathons. Milage has been about 50 per week but lately I have reduced a bit. Also, started doing a bit of stand up paddle boarding now and then 2 weeks ago.


History of the injury:
Until last Sunday I have had zero problems for several months. I went for a 20 mile run and main part was in a forrest with lots of uneven surface, ascents and descents. About 15 miles in I started to feel a bit of nagging along the inner edge of my foot. Completed the run and nothing was felt after the run.

Tuesday I went for a 8 mile run. After a mile or so I felt the nagging again, but nothing major.

Wednesday a very easy 4 mile run, no pain or nagging.

Thursday planned to do a 10 mile run with 4 miles at tempo pace. No pain during the first 2 miles of warm up or the first 2 miles of the main set but then over the course of a few hundred meters I developed sharp pain on the inner arche of the foot. I decided to walk home but for some reason I decided to try to massage and stretch. Sat down and pointed my toes upward while I massaged the inner edge of the foot. Tried to run and it was possible at easy pace

Friday 3 miles easy run, no pain

Today I did 14 miles easy run (have an ironman in 8 weeks so wanted to see if I could get the run in). No pain at all first 12 miles, last 2 miles I had some pain but only when running downhill. Also, stretched the calf (no massage) and it seemed to help.

Summary of symptoms:
- pain when running. Pain is dispersed along the inner edge of the foot. It is hard to pinpoint exactly where it is. Last Sunday it felt like the sole of the foot on the left side of the right foot so thought it was PT. Now I cannot really pinpoint it when running it seems to be along the entire edge of the foot but more towards the front than towards the back of the foot
- massage of the arch/edge of the foot as well as stretching seems to provide temporary releive of the pain and I can continue to run
- only today, after the long run, the pain has become in a specific spot. When I touch the "n spot" (a bump of bone that sort of sticks out on the inside of the navicular) from below I feel some light pain, but not when I push it from the top or other sides. Also, between the n spot and the heel there is no pain but when I rub a finger from the n-spot and forward towards the toes I have some light pain/soreness for about 1 inch
-- as long as I run on flat, even surface at my easy pace (not recovery) I can run without pain for up to 90 minutes

Possible injuiries:
It could be a stress fracture and I am going to get a MRI scan to figure out. Today I saw and orthopedic doc and he said it is like tendonitis but he is not sure so we will do the mri to confirm.

However, what makes me doubt it is sfx is that I can stretch/massage it away and the pain of the n spot is not when pressing it from above, only from below. Also, when I do the one leg jump test I have no real pain but a bit of soreness about 0,5 inch in front of the n-spot. I tend to think and hope it is some sort of inflamation of strain. Actually it feels quite tight in the ankle Could be posteior tibal tendonitis but there are no clear PTTD symptoms either


Has anyone experienced something similar? What was it? What did you do about it?